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Published on: August 15, 2018
ThMn12-type phases for magnets with low rare-earth content: Crystal-field analysis of the full magnetization process
I S Tereshina1, N V Kostyuchenko2,3, E A Tereshina-Chitrova4
1Faculty of Physics, Lomonosov Moscow State University, 119991, Moscow, Russia. irina_tereshina@mail.ru.
Abstract:
Rare-earth (R)-iron alloys are a backbone of permanent magnets. Recent increase in price of rare earths has pushed the industry to seek ways to reduce the R-content in the hard magnetic materials. For this reason strong magnets with the ThMn12 type of structure came into focus. Functional properties of R(Fe,T)12 (T-element stabilizes the structure) compounds or their interstitially modified derivatives, R(Fe,T)12-X (X is an atom of hydrogen or nitrogen) are determined by the crystal-electric-field (CEF) and exchange interaction (EI) parameters. We have calculated the parameters using high-field magnetization data. We choose the ferrimagnetic Tm-containing compounds, which are most sensitive to magnetic field and demonstrate that TmFe11Ti-H reaches the ferromagnetic state in the magnetic field of 52 T. Knowledge of exact CEF and EI parameters and their variation in the compounds modified by the interstitial atoms is a cornerstone of the quest for hard magnetic materials with low rare-earth content.
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